1. Field of the Invention
The present invention relates to a binding machine for reinforcing bars which adjusts a feed of a binding wire according to the diameter of the reinforcing bars to be bound or the diameter of the loop of the binding wire wound round the reinforcing bars.
Furthermore, the present invention also relates to a binding machine for reinforcing bars in which the diameter of the reinforcing bars to be bound is discriminated and both a feed and a binding force of a wire necessary for binding are determined according to the diameter of the reinforcing bars.
2. Description of the Related Art
In general, in a binding machine for reinforcing bars, a binding wire is sent outside the reinforcing bars from a bending guide arm arranged at an end of a binding machine body so that the binding wire can be formed into a loop, and a portion of the loop is twisted so as to bind the reinforcing bars. In this binding machine for reinforcing bars, a feed of the binding wire is set constant at all times. That is, even if the reinforcing bars are thick or thin, the binding wire is sent out from the end of the guide so that it can be wound round the reinforcing bars three times. After the binding wire has been sent out, a rear end of the binding wire is cut off from the binding wire on the binding machine body side, and a portion of the binding wire, which is wound round in a loop-shape, is twisted by a twisting means arranged on the binding machine body side.
In this connection, the binding wire is sent out so that both end portions of the binding wire can be located at positions on the opposite side to the twisting section. The reason is described as follows. When the binding wire is wound round the reinforcing bars three times in such a manner that both end portions of the binding wire are located on the opposite side to the twisting side of the binding machine, the number of the binding wires on the twisting side becomes four (the number of the binding wires on the opposite side except for both end portions becomes three). Therefore, the reinforcing bars can be strongly twisted.
However, when the reinforcing bars are bound by the binding wire of the same length irrespective of the diameter of the reinforcing bars, as shown in FIG. 12(a), in the case where the diameter of reinforcing rod xe2x80x9caxe2x80x9d is large, height h1 from the end of wire xe2x80x9cbxe2x80x9d to reinforcing rod xe2x80x9caxe2x80x9d is relatively small. However, as shown in FIG. 12(b), in the case where the diameter of reinforcing rod xe2x80x9caxe2x80x9d is small, height h2 from the end of wire xe2x80x9cbxe2x80x9d to reinforcing rod xe2x80x9caxe2x80x9d becomes relatively large.
The same thing can be seen in the case where tensile strength of the binding wire is changed according to the condition of use. When the binding wire is wound round the reinforcing bars, it is curled by the action of the bending guide arm. In this case, whether the bending wire can be easily curled or not is decided by the tensile strength of the bending wire. In accordance with that, the diameter of the loop of the bending wire is changed. Since a feed of the binding wire is constant, as shown in FIG. 13, when the diameter of the loop is changed, positions of end portions xe2x80x9cpxe2x80x9d, xe2x80x9cqxe2x80x9d of respective wires b1, b2 are changed according to the tensile strength. Accordingly, even if the diameters of the reinforcing bars to be bound are the same, when the diameter of the loop is large, height h3 from the end of wire xe2x80x9cb1xe2x80x9d to reinforcing bar xe2x80x9caxe2x80x9d is small as shown in FIG. 14(a). On the other hand, when the diameter of the loop is small, height h4 from the end of wire xe2x80x9cb2xe2x80x9d to reinforcing bar xe2x80x9caxe2x80x9d becomes large as shown in FIG. 14(b).
When height from the end of wire xe2x80x9cb,xe2x80x9d xe2x80x9cb1xe2x80x9d or xe2x80x9cb2xe2x80x9d to reinforcing bar xe2x80x9caxe2x80x9d becomes large as described above, the following problems may be encountered. When concrete 30 is placed after the reinforcing bars have been bound by the binding wire, height h2, h4 of the end portion of wire xe2x80x9cb,xe2x80x9d or xe2x80x9cb2xe2x80x9d becomes larger than thickness W of concrete in some times. In this case, the end portion of the binding wire is exposed from the surface of cured concrete. Accordingly, the exposed portion of the binding wire comes into contact with air and corrodes. When this corrosion spreads inside the concrete, the concrete tends to deteriorate.
As another aspect of a conventional binding machine for reinforcing bars, it is noted that a binding wire is sent in a loop-shape to the outside of the reinforcing bars from a bending arm which is arranged at an end of the binding machine body, and a portion of the loop is held by a twisting hook and twisted by rotating the twisting hook until the fastening force (torque) reaches a predetermined value, so that the reinforcing bars can be bound by a constant torque at all times. In this case, since the diameter of the reinforcing bar is stipulated by the standard, as long as a feed and a fastening torque of the wire are set according to the reinforcing bar of the maximum diameter, it is possible to bind the reinforcing bars of different diameters.
However, the following problems may be encountered in the binding machine of the prior art. Since the feed of the binding wire is always constant irrespective of the diameter of the reinforcing bar, a quantity of the wire to be used is constant even if the diameter of the reinforcing bar is small or large. Further, the twisting hook must be rotated until the fastening torque reaches a constant value. In the case of binding thin reinforcing bars, the twisting hook must be rotated over a longer period of time than the case of binding thick reinforcing bars. Accordingly, the binding wire is wasted, and the twisting hook must be operated over a long period of time.
Accordingly, It is a first object of the present invention to solve the above problems and provide a binding machine for reinforcing bars capable of reducing the height from the end of the binding wire to the reinforcing bars after binding by adjusting a feed of the binding wire according to the diameter of the reinforcing bars and the diameter of the loop.
In order to solve the above problems, the present invention provides a binding machine for reinforcing bars in which a binding wire is sent outside the reinforcing bars from a bending guide arm arranged at an end of the binding machine body so that the binding wire can be formed into a loop and then a portion of the loop is twisted so as to bind the reinforcing bars, comprising a feed adjustment mechanism for adjusting a feed of the binding wire according to the diameter of the reinforcing bars or the diameter of the loop of the binding wire wound round the reinforcing bars.
Furthermore, it is a second object of the present invention to provide a binding machine for reinforcing bars capable of enhancing the efficiency of binding by reducing a quantity of the binding wire to be used and also by reducing the binding time when the quantity of the binding wire to be fed is automatically adjusted according to the diameter of the reinforcing bar and the binding force is adjusted at the same time.
In order to solve the above problems, the present invention provides a binding machine for reinforcing bars in which a binding wire is sent outside the reinforcing bars from a bending guide arm arranged at an end of the binding machine body so that the binding wire can be formed into a loop and then a portion of the loop is twisted so as to bind the reinforcing bars, comprising a discriminating mechanism for discriminating the diameter of the reinforcing bars arranged at an end of the binding machine body, wherein a feed and a binding force of the wire is controlled according to the result of discrimination conducted by the discriminating mechanism.